Related

South African runner Caster Semenya's muscular physique helped propel her to victory during the 800 meters at Wednesday night's world track and field championships in Berlin. Now that physique, coupled with an ongoing gender verification test, is fueling suspicion that Semenya could be stripped of her medal because she is actually a he.

Semenya, 18, came to the world's attention on July 30 after winning the African Junior Championships in Mauritius. There, she posted 1:56.72, the fastest 800-meter run of the year  even when including senior-level competitors. Competing in her first senior championship on Wednesday, Semenya once again clocked the fastest time of the year  1:55.45  and finished a whopping two seconds ahead of the defending world champion. (Read "A Brief History of the World's Fastest Human.")

That astonishing margin of victory only added to the speculation that had started after Semenya's win in July  could the women's 800-meter world champion be a man? Ahead of the Aug. 19 final, officials from the International Association of Athletics Federations (IAAF), track and field's governing body, confirmed that Semenya had agreed to a gender-testing process that began in South Africa and was ongoing in Germany. Officials wouldn't give details of the testing, but did say that it involves an endocrinologist, a gynecologist, a psychologist, and both internal and external examinations.

IAAF director of communications Nick Davies stressed that the organization does not believe Semenya has been masquerading as a woman to give herself an unfair advantage. "It's a medical issue. It's not an issue of cheating," he told reporters before the final. Davies also said that the IAAF was trying to handle this sensitive situation as delicately as possible. "She is a human being who was born as a woman and who has grown up all her life as a woman, but who is now in a position where this is being questioned." Because there is not yet any scientific evidence that Semenya is a man, officials gave her "the benefit of the doubt" and the all clear to race on Wednesday.

Speaking from the rural village of Seshego in South Africa's northeastern Limpopo province, Semenya's mother Dorcus told the country's Star newspaper that she felt jealousy had motivated the rumors about her daughter. "If you go [to] my home village and ask any of my neighbors, they would tell you that Mokgadi [Caster] is a girl," she said. "They know because they helped raise her."

Semenya's coach, Michael Seme, also dismissed the claims. "I can give you the telephone numbers of her roommates in Berlin," he told South African news site News24. "They have already seen her naked in the showers and she has nothing to hide."

Seme's suggested test may seem crude, but there's a precedent for it in the world of athletics. At the 1936 Berlin Olympics, in the very same stadium where Semenya won her world title, rumors swirled that 100-meter runners Stella Walsh (nicknamed "Stella the Fella") and her rival Helen Stephens were men. After Stephens took the gold metal, the Olympics committee performed a manual check on her external genitals  and concluded that she was, in fact, a woman. And prior to the 1966 European athletics championships, female competitors were made to walk in so-called nude parades so that a committee could confirm their gender.

But Dr. Rob Ritchie, a urological surgeon at Oxford University and the author of "Intersex and the Olympic Games," a recent article in the Journal of the Royal Society of Medicine, says that determining someone's sex is not so simple, and that external genitalia can be misleading. A post-mortem on Stephens' body in 1980 revealed that she had "ambiguous genitalia." The post-mortem didn't go into specifics, but those genitalia could have been a small penis that was mistaken for an enlarged clitoris, or a small scrotum that resembled labia. (Read "Feeling Betrayed by Marion Jones.")

Ritchie notes that female athletes who in the past have been suspected of being men may have suffered from Androgen Insensitivity Syndrome (AIS), a condition in which a person who is genetically male  that is, their 23rd chromosome pair is XY  is resistant to androgens, the male sex hormones that include testosterone. As a result, the testes present in that person's abdomen never descend, and neither they nor their parents ever realize they are actually boys. Those with complete AIS will have a totally female body on the outside, but will lack ovaries and a uterus. Others may demonstrate partial AIS. "They are partly sensitive to the male hormone so they might develop some male characteristics," he says. "They may well be a bit more muscular and have facial hair."

It's those characteristics that Semenya's competitors see in the world champ, leading them to predict  and hope  that her forthcoming gender results will leave her ineligible to compete with women. "Just look at her," barked Mariya Savinova, the fifth-place finisher from Russia, following Wednesday's race. Italian Elisa Piccione, who finished sixth, was equally severe: "These kinds of people should not run with us. For me, she's not a woman. She's a man." She also outran them both  and not even a gender test can change that.